Measuring device for the contactless measurement of an angle of rotation

ABSTRACT

A measuring instrument for contactless detection of an angle of rotation γ is comprised of a supporting plate ( 14 ) made of soft magnetic material, which serves as a rotor. Two segments ( 16, 17 ) that are separated by a slot ( 21 ) and a spacing gap ( 22 ) are disposed in a plane in relation to the supporting plate ( 14 ). The supporting plate ( 14 ) is attached to the axle ( 11 ), whose projection ( 12 ) or the axle ( 11 ) itself is comprised of magnetically conductive material. The supporting plate ( 14 ) has a magnet ( 15 ) disposed on it, which is embodied as smaller than the angle of rotation γ to be measured. The magnet ( 15 ) can be embodied of one or several parts. Through the disposition of the magnet ( 15 ), it is possible to produce different sections in the measurement curve detected by the measurement instrument, e.g. plateaus or sections which deviate from the linear measurement line.

PRIOR ART

The invention is based on a measuring instrument for contactlessdetection of an angle of rotation. DE-OS 196 34 281.3 has disclosed asensor which is disposed in three superposed planes. The rotorconstitutes the middle plane, wherein it is comprised of the supportingplate for a permanent magnet. The supporting plate itself is comprisedof magnetically nonconductive material so that the magnetic flux travelsvia the two other planes, i.e. the stator, and is dispersed with the aidof two spacers which are disposed between the two planes of the stator.The shaft or the projections of a shaft that is attached to the rotorhas no influence on the magnetic flux. With the sensor, a relativelylarge angular range can in fact be measured without a change of sign,but it is relatively large in terms of the axial direction due to beingconstructed of three parallel planes.

Furthermore, in potentiometers, it is known to produce a brokenmeasurement line by subdividing the contact paths in the vicinity of theflattening.

ADVANTAGES OF THE INVENTION

The measuring instrument for contactless detection of an angle ofrotation according to the invention has the advantage over the prior artthat the sensor has a relatively small size in the axial direction. Itis comprised of only two planes. The supporting plates of the permanentmagnet which represents the rotor is simultaneously also used to conveythe magnetic flux. Furthermore, the shaft or axle supporting the rotoris included in the conduction of the magnetic flux, as a result of whichadditional magnetic flux conducting parts are rendered unnecessary.Furthermore, this design reduces the number of parts and the assemblycosts involved with them.

By varying the length of the magnet or dividing it into individualsections, it is simple to produce a measurement curve with one or moreflattenings.

Due to its simple design, the sensor can be integrated with a relativelylow assembly cost into various systems, e.g. a throttle measurementdevice, a pedal module for a gas pedal-travel sensor or can be used asan independent sensor in throttle valve transmitters or a body springcompression device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 4 show different views of or sections through a firstexemplary embodiment.

FIG. 1 is a longitudinal section in the direction X according to FIG. 3,

FIG. 2 shows a section B—B according to FIG. 4,

FIG. 3 shows a top view in the direction Y according to FIG. 1, and

FIG. 4 is a longitudinal section in the direction A—A according to FIG.3.

FIGS. 5 and 6 show the magnetic flux with an angular rotation of zerodegrees and an induction of B=zero,

FIGS. 7 and 8 show the corresponding magnetic flux with an angularrotation α and an induction of B=Max,

FIGS. 9 and 10 show the magnetic flux in the angular range β and in theplateau region with an induction of B=Max,

FIG. 11 shows the corresponding curve of the induction B over the totalangle of rotation γ (γ=α+β).

FIGS. 12 to 23 show other exemplary embodiments, wherein

FIGS. 12 to 15 show an embodiment with a two-part magnet,

FIGS. 16 to 19 show a magnet with a first slotted form and

FIGS. 20 to 23 show a two-part magnet with a slot in the support,

FIGS. 24 to 30 show the magnetic flux curve over the angle of rotation,and

FIGS. 31 and 32 show an embodiment with a radially magnetized magnet.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIGS. 1 to 4, a sensor is labeled 10, which with the aid of an axle11, is connected to a component, not shown, whose rotational movement isto be determined. A projection 12 is attached to the end face of theaxle 11 so that a shoulder 13 is produced on which a supporting plate 14is centrally placed, which simultaneously serves as a rotor. The axle11, the projection 12, and the supporting plate 14 can be embodied bothas separate components and as a single component. An annular permanentmagnet 15 is disposed on the supporting plate 14 with the greatestpossible radial distance from the center point, i.e. from the attachmentpoint of the axle 11. The greater this distance, the better theresolution of the measurement signal. The permanent magnet 15 can beembodied as a sector of a circle (circle segment) or part of a circularring. Its angular range α, however, is smaller than the to-be-determinedmaximal angle of rotation γ of the component to be monitored andmeasured. As can be seen from the depictions in FIGS. 2 and 3, theangular range α of the permanent magnet 15 in this exemplary embodimentis approx. 100 degrees; the total working measurement range, however, isγ=180 degrees. The differential angle β would create the plateau P shownin FIG. 11. The permanent magnet 15 is furthermore polarized in theaxial direction, i.e. perpendicular to the supporting plate 12. Thesupporting plate 14 is comprised of magnetically conductive, inparticular soft magnetic material. According to the invention, the axle11 and the projection 12 or at least the projection 12 is comprised ofmagnetically conductive, in particular soft magnetic material.

In a second plane above the permanent magnet 15, a stator, which iscomprised of two segments 16, 17, is disposed parallel to and spacedslightly apart from the supporting plate 14. In so doing, the segment 16encompasses the projection 12 with an arc 19. In this exemplaryembodiment, the arc 19 is embodied as an arc of a circle. However, adifferent contour is also conceivable. The essential thing, however, isthat a magnetically conductive connection be possible.between theprojection 12 and the segment 16. The gap 20 between the axle 11 and thearc 19 must therefore be embodied as small as possible. A continuous gapis embodied between the two segments 16, 17 and in the exemplaryembodiment according to FIGS. 1 to 4, has two identically embodied outersections 21 and a central spacing gap 22 disposed in the vicinity of thearc 19. With regard to the spacing gap 22, it is important that as closeas possible to none of the magnetic flux produced by the permanentmagnet 15 is possible between the segments 16 and 17, i.e. in thisexemplary embodiment, in the vicinity of the arc 19. The spacing gap 22can therefore be filled with air or with another magneticallynonconductive material. If the spacing gap 22 is filled with air, forexample, then it must be embodied as larger than the gap 21 in order toachieve this above-mentioned effect. Instead of air, a differentmagnetically nonconductive material can also be selected. The gap 21 andthe spacing gap can also be filled with different materials. A magneticfield-sensitive element 25, such as a Hall-effect digital switch, amagnetic transistor, coils, magnetoresistive element, or a Hall element,is disposed in at least one of the gaps 21, approximately in the middle.In this connection, it is important that the magnetic field-sensitivecomponent has as linear as possible a dependency of its output signal onthe magnetic induction B. In FIGS. 1 to 4, a respective measurement isdepicted with the aid of a single magnetic field-sensitive element 25,in this instance a Hall element. In this instance, the element 25 mustbe disposed as close as possible to the middle in the gap 21. However,it would also be possible, for example, to dispose a respective element25 in each of the two gaps 21 in order, for example, to be able toexecute a so-called redundant measurement (safety measurement). It wouldalso be conceivable to dispose two elements in one gap. If one magneticfield-sensitive element 25 is disposed in only one gap 21, as shown inFIG. 3, then the opposite gap 21 can also be the size of the spacing gap22 and consequently have the magnetically nonconductive function of thespacing gap 22.

FIG. 11 shows the course of the characteristic curve of the magneticinduction B in the element 25, e.g. a Hall element, over the angle ofrotation γ of the axle 11. It is clear that with an angle of rotation γof 0°, the induction B is likewise 0, while at the maximal angle ofrotation γ=max, the maximal induction value is also achieved. In thisexemplary embodiment, the maximal angle of rotation γ is reached at180°. The position of the sensor 10 with an angle of rotation of 0° isshown in FIGS. 5 and 6. It is clear that the magnetic flux travels fromthe permanent magnet 15, via the air gap 100 to the segment 17, fromthere via the slight gap 20, which allows the rotor to move in relationto the stator, to the projection 12 and from there, via the supportingplate 14, back to the permanent magnet 15. As can be seen in particularin FIG. 6, the magnetic flux is controlled so that with an angle ofrotation of 0°, it does not travel through the element 25 so that nomagnetic induction B can occur in the element 25. If the axle 11 andhence the supporting plate 14 with the permanent magnet 15 is nowrotated, then the magnetic flux traveling through the element 25 isincreased and the linear measurement line H shown in FIG. 11 isproduced. In FIGS. 5 to 10, it should be noted that the rotor is movingcounterclockwise. At the end of the measurement line H, i.e. at point B,the permanent magnet 15 has just passed completely through the gap 21.It also indicates that the permanent magnet 15 is now disposedcompletely underneath the segment 16. This position B at the angle ofrotation α also represents the position of the maximal magnetic flux ofthe permanent magnet 15 via the gap 21. With further rotation by theangular range β in order to achieve the total rotation range γ no changein the induction B occurs in the measurement gap 21 and consequently inthe measurement element 25. As a result, a plateau region P is producedin the graph according to FIG. 11. FIGS. 9 and 10 show the end positionat point C after the further rotation by the angle β, i.e. after thetotal rotation range γ. It is clear, particularly from FIGS. 8 and thegap 21, nearly the entire magnetic flux is conveyed through the element25 and as a result, a maximal possible magnetic induction B is producedin the element 25. Furthermore, it is also clear from these two FIGS. 8and 10 that the spacing gap 22 causes nearly all of the magnetic linesto travel via the gap 21 and consequently through the element 25. Thismeans that as close as possible to no magnetic flux can travel throughthe spacing gap 22.

It is essential to the invention that the permanent magnet 15 is smallerthan the entire measurement range γ and is smaller than the segment 17serving as a flux conducting part. In the preceding exemplaryembodiments, the permanent magnet 15 was embodied of one piece and wasdisposed on the support 14 so that the beginning of the permanent magnetwas also disposed at the beginning of the rotation range. In theexemplary embodiment according to FIGS. 12 to 15, the permanent magnetis now embodied of two parts. This two-part design shifts the plateauregion P, which corresponds to the rotation range β of the sensor 10,between two linearly extending curve sections (FIG. 30). The two annularor segment-shaped permanent magnet parts 15 a and 15 b can be ofdifferent sizes or of the same size. The two parts are magnetized in thesame direction. Because the measurement range β is now disposed betweenthe two permanent magnet parts 15 a and 15 b, the plateau region P isshifted into the course of the measurement line A so that acharacteristic curve is produced that is analogous to the one in FIG.30. FIG. 30 shows a characteristic curve in which the two permanentmagnet parts 15 a and 15 b were the same size. Furthermore, it wouldalso be possible for there to be more than two permanent magnet parts,i.e. three, four, etc. It would therefore be possible to produce acorrespondingly desired number of plateaus in the measurement line.Instead of a permanent magnet, it would also be possible to also producemagnetized regions on the supporting plate. This embodiment could beused for all of the exemplary embodiments mentioned here. Controls canbe carried out with the aid of the plateau(s) or sections that deviatefrom the actual measurement curve.

While in the preceding exemplary embodiments, there is a separation ofthe two permanent magnet parts 15 a and 15 b, the parts can also beconnected to each other by a small intermediary piece. A correspondingexemplary embodiment is shown in FIGS. 16 to 19. In FIG. 17, theintermediary piece 50 is disposed on the inside, i.e. it connects theinner radius of the two permanent magnet pieces 51 a and 51 b to eachother. Naturally, it would also be possible to dispose the connectingpiece 50 at the outer edge or in the middle. Because of this connectingpiece 50, the measurement curve in the vicinity of the angle of rotationβ no longer extends flat as a plateau, as in the preceding exemplaryembodiments and as shown in FIG. 11, but depending on the width of theconnecting piece 50, this region of the graph has a rise in the rotationrange β. The rise can be influenced by the dimension, in particular theradial width. This means that it is also possible for there to be anintermediary piece that is wider than the permanent magnet parts andconsequently a steeper course of the curve can be achieved in thisregion than in the vicinity of the permanent magnet parts.

The exemplary embodiment in FIGS. 20 to 23 likewise has a two-partpermanent magnet as shown in a similar fashion in FIGS. 12 to 15. Thetwo permanent magnet parts 61 a and 61 b here are the same size, i.e.have the same angular range. This means that the angular range α1=α2.The two permanent magnet parts 61 a and 61 b are disposed so that theangular range β is disposed between the two parts. In addition, a slotis also embodied in the support 14 in the region β. This slot 62 servesto achieve a relatively sharp transition between the linearly extendingcharacteristic curve and the plateau region P in the measurement rangeβ. FIGS. 21 and 20 also show that the supporting plate 14 a does nothave to be an entire disk, but serves only as a supporting surface forthe permanent magnet parts 61 a and 61 b and for fastening as a rotor tothe axle 11 or its projection 12.

Whereas a magnetic flux in the preceding exemplary embodiments wascontrolled via the magnetically conductive projection 2 of the axle 11,in FIGS. 24 to 29 and in the corresponding graph 30, an embodiment of asensor 70 is shown in which the magnetic flux does not travel via theaxle and/or a projection of the axle, but rather is controlled via areturn flux part 72 attached to a segment 17 a of the stator thatfunctions as a flux conducting part. It is clear in FIG. 24 that asupport 14 b is disposed on the axle 11 a and has the same properties asthe support 14 or 14 a in the preceding exemplary embodiments. In asecond plane above supporting plate 14 b, which serves as a rotor, thereis a stator which is comprised of two segments 16 a and 17 a. A magneticfield-sensitive element 25 a is disposed in the slot 21 a between thetwo segments 16 a and 17 a. An element of the kind described in theother exemplary embodiments can be used as the magnetic field-sensitiveelement 25 a. A return flux part 72 is disposed on the segment 17 a andencompasses the entire circular circumference surface of the segment 17a. It has a length that protrudes beyond the supporting plate 14 b. Likethe two segments 16 a and 17 a, it is made of magnetically conductivematerial. It is also clear from FIG. 25 that the permanent magnetdisposed on the supporting plate 14 b is comprised of two parts 71 a and71 b. The two parts 71 a and 71 b are of the same size, which means thatthe angular range α1=α2. The measurement range β is once again disposedbetween the two permanent magnet parts 71 a and 71 b. FIGS. 24 and 25now show the position with an angle of rotation γ=0° and an inductionB=0. With counterclockwise rotation of the axle 11 a and consequently ofthe supporting plate 14 b, the first magnet part 71 a is moved acrossthe gap 21 a and is disposed to an ever increasing degree in thevicinity of the segment 16 a. FIGS. 26 and 27 now show the position whenthe measurement range β is disposed over the gap 21 a. As long as themagnet part 71 a is moving underneath the segment 16 a, thecharacteristic curve rises in linear fashion as shown in FIG. 30. Assoon as the entire permanent magnet part 71 a has passed the gap 21 a,the plateau P begins, which corresponds to the measurement range β. Assoon as the magnet part 71 b begins to move under the segment 16 a, themeasurement line rises again in linear fashion and reaches the maximalinduction B=max as soon as the permanent magnet part 71 b, i.e. bothpermanent magnet parts 71 a and 71 b, are disposed completely underneaththe segment 16 a. FIGS. 28 and 29 then show the position of the sensor70 with a maximal angle of rotation position γ=max and a maximalinduction B=max.

The measurement line in FIG. 30 has therefore two different risingslopes (it does not change sign).

The sensors described in the exemplary embodiments are suited, forexample, for installation in a throttle valve adjusting unit. This unitassists in detecting the angle of rotation of a throttle valve for amotor control. In this connection, the segments 16, 17 of the stator canbe installed directly in the cover of the throttle valve adjusting unit.Since the cover is comprised of plastic, the segments 16, 17 can beinjection molded into the cover. The two segments 16, 17 of the statorcould also possibly be clipped into the cover.

FIGS. 31 and 32 now show an embodiment of an angle sensor 80 in whichthe permanent magnet or the permanent magnet parts are magnetized in theradial direction. In the angle sensor 80, one of the segments 95 isconnected by means of a bridge 96 to an outer annular housing part 93.The second segment element 97 has no connection to the housing part 93,i.e. there is no magnetically conductive connection between the segment97 and the housing part 93. Because of the bridge 96, the angular rangeto be determined is consequently limited, i.e. it is not possible totake measurements over an angle of approximately 200°. In thisembodiment, the segment 95, the bridge 96, and the housing part 93 canadvantageously be produced as a one-piece component made of softmagnetic material, e.g. stacked transformer plates or sintered material.Naturally, it is also possible here to embody the segments 95, 97 notonly symmetrically but also asymmetrically. The magnetic field-sensitiveelement 99, which can be embodied the same way as in the above-describedexemplary embodiments, is disposed in the slot 98 between the twosegments 95 and 97. In the depiction according to FIG. 31, the permanentmagnet 91 a, 91 b disposed in the slot 100 embraces the segment 97. Thismeans that the permanent magnet in turn is comprised of at least twopermanent magnet parts 91 a and 91 b or of a single permanent magnetwhich embraces an angular range smaller than the segment 97. Thepolarization direction of the permanent magnet or the two permanentmagnet parts is oriented in the radial direction. This means that themagnetization direction is directed from the segment 97 toward thehousing part 93 or in the opposite direction. FIGS. 31 and 32 do notshow that the permanent magnet or the two permanent magnet parts 91 aand 91 b are in turn disposed on a supporting plate which is connectedto the rotating axle. In this connection, FIG. 31 shows the position ofthe permanent magnet with an angle of rotation γ=0 and FIG. 32 shows theposition with a maximal angle of rotation γ=max. The measurement lineproduced during the rotating motion corresponds analogously to thecharacteristic curve shown in FIG. 30.

What is claimed is:
 1. A measuring instrument for contactlessdetermination of rotational movement of a component, comprising a rotorconnectable with a component; a stator rotatable relative to said rotorwith an air gap between said stator and said rotor, said stator beingcomposed of at least two segments which are separated by a magneticallynon conductive gap; a magnet arranged on said rotor, at least onemagnetic field-sensitive element disposed in said magnetically nonconductive gap, at least one part of said stator having a magneticallyconductive connection to said rotor, said rotor being composed of amagnetically conductive material, said magnet being smaller than anangle of rotation between said stator and said rotor to be measured sothat there are two different exclusively ascending slopes in a measuringcurve which does not have a change of sign.
 2. A measuring instrument asdefined in claim 1, wherein said magnet is composed of a number of partswhich are separated by a section of non magnetic material.
 3. Ameasuring instrument as defined in claim 1, and further comprising atleast one return flux part which protrudes beyond said rotor and isdisposed in one of said segments.
 4. A measuring instrument as definedin claim 1, and further comprising at least one return flux partarranged on one of said segments, said rotor protruding beyond saidreturn flux part.
 5. A measuring instrument as defined in claim 1,wherein said rotor has an axle with at least one region of magneticallyconductive material extending from said rotor to a part of said statorwhich has a magnetically conductive connection to said rotor, one ofsaid magnetically non conductive gaps impeding a magnetic flux of saidmagnet and controlling it so that it travels via at least the other ofsaid magnetically non conductive gaps, said one magnetically nonconductive gap being larger than said other magnetically non conductivegap.
 6. A measuring instrument as defined in claim 5, wherein said atleast one region of said axle and also said rotor are composed of softmagnetic material.
 7. A measuring instrument as defined in claim 5,wherein said stator has a part with a projection into which said atleast one region of said axle protrudes.
 8. A measuring instrument forcontactless determination of rotational movement of a component,comprising a rotor connectable to a component; a stator which iscomposed of a magnetically conductive material and is located relativeto the rotor so that an angle of rotation between a stator and a rotoris to be detected, said stator and said rotor having an air gaptherebetween, said stator also having at least one air gap; at least onemagnetic field-sensitive element located in said at least one air gap ofsaid rotor; at least one magnet having at least one portion arranged insaid rotor, said stator being composed of a plurality of parts, one ofsaid parts having no magnetically conductive connection to the remainingparts so that a division of a magnetic flux of said magnet takes place,so that at least a first part of the magnetic flux flows through saidmagnetic field-sensitive element, said magnet being smaller than anangle of rotation to be measured between said rotor and said stator, sothat there are two different exclusively ascending slopes in a measuringcurve which does not have a change of sign.
 9. A measuring instrument asdefined in claim 8, wherein said magnet is composed of a number of partswhich are separated by a section of non magnetic material.
 10. Ameasuring instrument as defined in claim 8, and further comprising atleast one return flux part which protrudes beyond said rotor and isdisposed in one of said segments.
 11. A measuring instrument as definedin claim 8, and further comprising at least one return flux partarranged on one of said segments, said rotor protruding beyond saidreturn flux part.
 12. A measuring instrument as defined in claim 8,wherein said rotor has an axle with at least one region of magneticallyconductive material extending from said rotor to a part of said statorwhich has a magnetically conductive connection to said rotor, one ofsaid magnetically non conductive gaps impeding a magnetic flux of saidmagnet and controlling it so that it travels via at least the other ofsaid magnetically non conductive gaps, said one magnetically nonconductive gap being larger than said other magnetically non conductivegap.
 13. A measuring instrument as defined in claim 8, wherein said atleast one region of said axle and also said rotor are composed of softmagnetic material.
 14. A measuring instrument as defined in claim 8,wherein said stator has a part with a projection into which said atleast one region of said axle protrudes.
 15. A measuring instrument forcontactless determination of rotational movement of a component,comprising a stator; a rotor rotatable relative to said stator and whoseangle of rotation relative to said stator is to be detected, so that anair gap is provided between said stator and said rotor; a magnetarranged on said rotor, said stator being composed of at least twosegments which are separated by a magnetically non conductive gap; atleast one magnetic field-sensitive element arranged in said magneticallynon conductive gap, at least a part of said stator having a magneticallyconductive connection to said rotor, said rotor being composed of amagnetically conductive material, said magnet being composed of aplurality of parts, at least two parts of said magnetic being connectedto each other via an intermediate piece, so that there are at least twodifferent exclusively ascending slopes in the measuring curve, whichdoes not have a change of sign.
 16. A measuring instrument as defined inclaim 15, and further comprising at least one return flux part whichprotrudes beyond said rotor and is disposed in one of said segments. 17.A measuring instrument as defined in claim 15, and further comprising atleast one return flux part arranged on one of said segments, said rotorprotruding beyond said return flux part.
 18. A measuring instrument asdefined in claim 15, wherein said rotor has an axle with at least oneregion of magnetically conductive material extending from said rotor toa part of said stator which has a magnetically conductive connection tosaid rotor, one of said magnetically non conductive gaps impeding amagnetic flux of said magnet and controlling it so that it travels viaat least the other of said magnetically non conductive gaps, said onemagnetically non conductive gap being larger than said othermagnetically non conductive gap.
 19. A measuring instrument as definedin claim 15, wherein said at least one region of said axle and also saidrotor are composed of soft magnetic material.
 20. A measuring instrumentas defined in claim 15, wherein said stator has a part with a projectioninto which said at least one region of said axle protrudes.
 21. Ameasuring instrument for contactless determination of rotationalmovement of a component, comprising a rotor composed of a magneticallyconductive material and connectable to a component; a stator arrangedrelative to said rotor so that an air gap is provided between saidstator and said rotor, said stator being provided with at least one airgap; at least one magnetic field-sensitive material located in said atleast one air gap of said rotor; at least one magnet having at least oneportion arranged in said rotor, said stator being composed of aplurality of parts, at least one of said parts of said stator having nomagnetically conductive connection to remaining parts of said stator sothat a division of a magnetic flux of said magnetic takes place, atleast a first part of said magnetic flux flowing through said magneticfield-sensitive element, said magnet being composed of a plurality ofparts so that at least two parts of said magnet are connected to eachother with an intermediate piece, so that there are at least twodifferent exclusively ascending slopes in a measuring curve which doesnot have a change of sign.